146 



LEAVES AND BUDS. 



erect, each leaflet being folded along the midrib and the side-veins as 

 well. As the leaf-stalk lengthens (the leaflets are sessile on its end), 

 the leaflets spread open and bend downwards. Later, the leaflets rise 

 up again and spread out horizontally ; meanwhile the stem of the bud 

 has been growing in length. The bud-scales fall off ; the white hairs 

 covering the leaflets become brownish and fall away. 



Here, as in Sycamore, it is easy to see, as the bud opens, that the 

 structures lying between the hard, externally visible scales and the 

 young foliage -leaves are intermediate in nature between bud-scales and 

 ordinary leaves. The buds usually open about the middle of April. 



179. Oak (see Art. 388). Here the leaves and buds are 

 arranged singly and spirally on the grey or brown twigs 

 (Fig. 51). In passing from any leaf, or bud, to the next one 

 directly above it, we go twice round the twig and pass four 



Pig. 51. Twig of Oak and Ground-plan of Bud. 



other leaves, or buds ; there are therefore five rows of leaves, 

 as can generally be seen on looking along the twig. The 

 buds, which are crowded at the tips of the twigs, are brown, 

 smooth, egg-shaped, and slightly five-angled. The clustering 

 of the buds towards the tip of each twig is of course simply 

 due to the upper leaves being clustered in this way so as to 



